Color display for sound reproducing systems



United [72} Inventor Gregory S. Marsh 90 Tidewater Road Henlopen Acres,Rehoboth, Del. 19971 [211 App]. No. 763,027 [22] Filed Sept. 26, 1968[451 Patented Dec. 29. I970 [54] COLOR DISPLAY FOR SOUND REPRODUCINGSYSTEMS 4 Claims, 1 Drawing Fig.

[52] U.S. Cl 84/464 [51] lnt.Cl A63j 17/00 [50] Field of Search 84/464[56] References Cited UNITED STATES PATENTS 3,228,278 l/l966 Wortman84/464 2,806,953 9/1957 Krauss 84/464 3038061 6/1962 OReilly 84/4643,474,774 10/1969 Johnson et al. 84/464 OTHER REFERENCES Blechman, FTransistor-Photocell Color Organ," Electronics World, Vol. 72, No. l,Ziff-Davis Publishing Co.. New York, July. 1964, pp. 41-43.

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Lawrence R.Franklin A!r0rne vBurns. Doane, Benedict, Swecker and Mathis ABSTRACT: Avariable color display for sound which is responsive to the combinationof the frequency and amplitude of the audio frequency signal. Thedisplay includes a plurality of signal channels, each containing aseries connected capacitor and neon tube with each capacitor havingdifferent capacitive values, connected in parallel whereby the neontubes turn on and off at different times and produce light outputs thatmay be of different intensities in response to the same audio signal.Photoresistors located with each neon tube control the voltage suppliedto different ones of a plurality of differently colored lamps. The lampsof different colors are thus selectively energized to produce a colordisplay which has a unique relation to audio frequency signals, andparticularly to music.

l 3e L. W 2 24 30 F- as PATENTED DEEZSISYB 5 9 INVENTOR. GREGORY 5, MAR5H BY 16mm M fimm m w ATTORNEYS COLOR DISPLAY FOR SOUND REPRODUCINGSYSTEMS BACKGROUND OF THE INVENTION The invention relates to a variablecolor display in response to audio frequency signals, and moreparticularly to a display where the individual colors are responsive tothe combination of frequency and amplitude of audio input signals.

Variable color displays have been used to produce a psychedelic effectduring musical performances. These prior displays have included aplurality of differently colored lamps which flash on and off during themusical performance, and in some cases, the displays have operated on apredetermined program by utilizing commutator switches to selectivelyactuate the lamps. The effect of such systems is too orderly and doesnot bear any correspondence to the music being played.

Other systems have overcome this problem by making the energization ofthe lamps responsive to the music itself. This has been accomplished byproviding a plurality of frequency selective paths including narrow bandfilters so that lamps of a particular color are energized in response toa particular frequency of sound. These systems, however, incorporatecomplex circuits which include expensive elements thereby making suchsystems relatively expensive. In addition, these systems produce asomewhat refined effect due to the precise selectivity of theirfrequency responsive paths.

It is the major object of this invention to provide a variable colordisplay for sound which can be produced with very inexpensive circuitcomponents and which produces a unique and intriguing color pattern inrelation to music because of being responsive to an unusual combinationof both frequency and of amplitude.

DETAILED DESCRIPTION Referring now to the drawing, which illustrates aschematic of a circuit embodying the present invention, a pair ofterminals 2 and 4 are adapted to be connected to a source of audiofrequency signals (not shown) such as the output of an amplifierconnected to a microphone, radio, tape or record player, or the like.Terminals 2 and 4 are connected through a variable resistance such aspotentiometer 6 having a movable tap .8, to the primary winding, whichmay for example have 8 ohms resistance, of a magnetic core transformer10.

The secondary winding of transformer 10 may have a resistance of between5 K and K ohms and hence produce an audio frequency signal voltage whichis somewhat higher than the voltage customarily supplied toloudspeakers.

Connected across the terminals of the secondary winding of transformer10 are three signal channels, each containing a series circuitconsisting of a capacitor 12, 14 or 16, and a neon tube 24, 26 or 28,respectively. Neon tubes 24, 26 and 28 are mounted in close proximitytophotoresistors 30, 32 and 34, respectively, which in turn areconnected in series with lamps 36, 38 and 40. Lamps 36, 38 and 40 are ofthree different colors, such as red, amber and blue, and are connectedto be energized from power, such as 1 17 volts AC at terminals 42 and44.

Neon lamps 24, 26 and 28 are of the type where the gas ionizes at apredetermined voltage and where the ionization extinguishes at asomewhat lower voltage. A suitable lamp is commercially available as anNE-2 neon lamp. This lamp is rated to operate with 117 volts, but willbecome conductive and produce light with an applied voltage somewhat inexcess of about 60 volts. When the applied alternating voltage is lessthan about 50 volts, ionization is lost and production of light ceases.

Photoresistors 30, 32 and 34 are mounted in light-tight housings 18, and22 with their respective neon lamps 24, 26 and 28. The photoresistor maybe secured against the envelope wall of the neon tube by a suitabletape, or adhesive, or the assembly may be potted in a suitable plastic.

Lamps 36, 38 and 40 may be of conventional type form such as a C-7-/ orD-33 available from General Electric Company.

In the operation of the foregoing circuit, audio frequency signals onterminals 2 and 4 are fed through the variable resistor 6 to the primarywinding of transformer 10. By adjusting the movable tap or resistor 6,the amplitude of the signal output from the secondary winding oftransformer 10 may be varied to thus obtain the desired response of thedisplay to the normal level of the incoming audio frequency signals.

The signal voltage is stepped up in the transformer 10 and appliedsimultaneously to all three neon lamps 24, 26 and 28 through capacitorsl2, l4 and 16, respectively. The relative impedance provided bycapacitors l2, l4 and 16 for a signal at any particular frequency in theaudio frequency signal varies in accord with their different capacitivevalues. Typical values of capacitance which may be used are 0.05, 0.036and 0.018 ,uf. The smallest capacitor presents the largest impedance,and hence its associated neon tube will not become a source of lightuntil after both of the other neon tubes have become light sources. Whenthe amplitude of a particular signal frequency exceeds a certain value,all three neon tubes become light sources; and the neon tubes associatedwith the capacitor having the lowest capacitive value will be the firstto become extinguished as the amplitude of the audio signal decreases,such as during a pause in speech or in music.

From the foregoing, it is evident that a loud audio signal, even at arelatively low frequency, can cause two or all of the neon tubes tobecome light sources. At a higher frequency, the same result can beachieved with a corresponding decrease in audio level. The intensity ofthe display light from lamps 36, 38 and 40 is controlled by the amountof resistance offered by photoresistors 30, 32 and 34. Hence, with anincrease of light output from a neon tube due to an increase in currentflow resulting from audio frequency signals of higher amplitude, thereis a corresponding increase in the intensity of the output from lamps36, 38 and 40.

By the appropriate adjustment of the variable resistor 6 after thedesired loudness of the sound fromspeaker 46 has been selected, it ispossible to obtain a variable color display where both the number ofdifferent colors that are displayed and the intensity of each displayedcolor increases as the loudness and the pitch of the music increase.

Obviously, four or more signal channels can be used where display lampsof four or more colors are desired. Also, where stereo sound systems areemployed, two units each indentical to the unit described above may beprovided, with a different unit for each channel of the stereo system.Each of lamps 36, 38 and 40 may be replaced by two more lamps of thesame color where a large area display unit is desired. A translucentplate over the lamps to minimize the apparent point source of each lampis also advantageous.

From the foregoing, it is evident that by the present invention, thereis provided a variable color light display responsive to audio frequencysignals where the number of components required is minimized, and allthe components are commercially available at relatively low cost whencompared with similar systems shown in the prior art. In accordance withthe invention, each of the series circuits connected to the secon darywinding of transformer 10 includes essentially an ionizable gas-filledglow tube and a capacitor, and therefore does not require componentsconstituting an amplifier stage.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

Iclaim:

1. Apparatus for producing a variable color visual display of an audiofrequency signal comprising:

a source of audio frequency signals;

a first plurality of series circuits each including essentially anionizable gas-filled glow tube and a capacitor, at least two of saidcapacitors having different values of capacitance, each of said circuitsbeing connected to said source of audio frequency signals; and

a secondplurality of series circuits each including a photoresistor anda lamp connected to be energized from a power source, at least two ofsaid lamps having a different color and each of said photoresistorsbeing illuminated by one of said glow tubes whereby said lamps ofdifferent colors are energized at different times in response to thesame frequency signals.

2. Apparatus as defined in claim 1 wherein said glow tubes are neon gastubes and the gas is ionized when applied voltage is in excess of about60 volts and ionization is extinguished when the applied voltage is lessthan about 50 volts.

3. Apparatus as set forth in claim 1 further including a transformerhaving a primary winding connected to receive said audio frequencysignals, and a secondary winding having output terminals, said firstplurality of series circuits being connected to terminals on saidsecondary winding, and a sensitivity control means for varying theresponsiveness of said display to the amplitude of said audio frequencysignals.

4. Apparatus as set forth in claim 3 wherein said sensitivity controlmeans consists solely of a-single variable resistor connected in seriescircuit arrangement with the primary of said transformer.

